A single mother who decided to go on a one-woman harassment campaign from her driveway. Her target? The family across the street. You'll see the tape, there's no denying what she did. But why she did it is the question. Here's amy robach. Reporter: The friendly sights and sounds of a neighborhood block party may seem typical, but make no mistake what's happening here is nothing short of miraculous. This is a great group of people in this neighborhood. But -- it's been that way for years. Reporter: A close knit community to a ghost town, all because of this woman. Lori christensen, a local government employee. Greg and kim huffman call her the neighbor from hell. But life in this minneapolis suburb hasn't always been so toxic. We were all very friendly. Kids would play with each other. She was a single mom. We would help her out with blowing her snow in the winter. Things like that. Reporter: The family says cordial turns to combative one day five years ago, because of a spat over nail polish between their young daughters. I didn't think it was that big a deal. So, I just went over to lori's and I said, this is what had gone on. And immediately she pretty much went off on me. She was yelling and -- Reporter: Screaming at you? Had she ever before? No, she had not. And I turned around and started to walk away. Reporter: But the huffmans were about to learn walking away from her wrath wouldn't be that simple. And just how vicious her attacks could get became clear when kim, a recovering alcoholic, suffered a dangerous relapse. Greg and my kids didn't know whether I was going to live. Collapsed in front of me. Reporter: She collapsed in front of you? Yeah. I had my son call 911. And I still remember standing in the garage and I heard that paramedic say, you know, we can't get a pulse. So -- Reporter: The commotion that day did not go unnoticed by christensen, who soon used the traumatic incident against kim. She starts swearing at me, you know, you fat whatever, you should have died. Why don't you drink some more scotch? And I had my two girls' hands and I just squeezed them and we kept walking. Reporter: She saw that you had a weakness. Yeah. Reporter: And she went for it? Uh-huh. Absolutely. Yeah. And it never stopped after that. Never stopped. high that police were now regular visitors to the once quiet neighborhood. And, at first, apprehensive authorities didn't know who to believe. It took quite awhile for kim and greg to convince me that this was not a he said-she said event. Reporter: Lynn bankes needed proof of the ongoing harassment. So, pressing record proved to be a game-changer in this conflict. As they say, a picture is worth 1,000 words. The videotapes supported what we were telling the police. Reporter: And that changed everything? It started changing everything. Way to go, jake. Reporter: When jake had a birthday party at home, the camera caught all of christensen's antics. The kids are out there sho shootisho shooting baskets and lori took out the remote control cars and, "i'm took drunk to drive." Calling me a son of an alcoholic in front of my friends, and my friends weren't aware of that. 911, what is your emergency. Reporter:911 was called, but christensen continued to thumb her nose at law enforcement. It was obvious that lori wasn't going to stop on our request and going to have to be more serious consequences for her. Reporter: In early 2010, the huffmans stopped engaging their neighborhood, and went to court to prohibit christensen from having any contact with them. To not respond to her when she was going after my kids was excruciatingly difficult. Reporter: Did you feel like you were trapped? Absolutely. We were trapped. That's just inexcusable. You're not allowed to drive another family into seclusion. Reporter: By the end of 2010, the huffmans say they were prisoners in their own home. Relegated to the backyard out of fear of what lori christensen might do next. They were right to be concerned. Because just across the street, she was forming a new way to torment then. Every time I turned the corner to come down our street, I knew there was going to be something. Reporter: And something soon became 25-foot signs covering christensen's garage, with humiliating messages aimed directly at the huffmans. Like, "i saw mommy kissing a breathalyzer." How often did she have signs up? She would put them up for a week, maybe they'd be down the following day. And then somebody came over to her house, they go back up. Reporter: That continued harassment, including this bizarre mock strip tease was a clear say lake of the restraining order. Escalating christensen's charges to a felony and landing her in a county work house for 30 days. Did you think, this is it? Finally ends now. Absolutely. Finally this is put to rest. This is over. Reporter: It wasn't? Not even close. Do you have anything at all to say? Reporter: If getting locked up didn't get christensen's attention, local news media were about to. I had a psychological evaluation, they said that if you were to have been a man, that this would not have been happening, but because I'm a single female, I have a very good job, I have the biggest house in the neighborhood -- Reporter: Did you or your officers ever ask her why? I'm sitting across from her, and I said, why can't you just stop this? And she looked me right in the eye and she said, it's my life long goal to make these people's life miserable. Reporter: But miserable seemed to better describe christensen's life. After continuing to disregard a judge's order to have no contact with the huffman's, this summer, she was arrested again and charged with three more felony counts. The so-called nightmare neighbor. This isn't her first offense. She's accused of serial ssment. Reporter: Before she could face those charges, though, a fed up judge threw her in jail for 90 days for violating her probation. And she lost her government job. But most importantly, christ christensen was banned from returning to her home. She had to stay a mile and a half away from her house. Reporter: It's for real. It's for sale. We're not going to let you act like this in this community. If you are just plain mean, there's going to be consequences. Reporter: Consequences that have left christensen facing a trial in october. She has pleaded not guilty. After five years, over 80 calls to police, almost 50 citations and enough mug shots to fill a photo album, finally, a victory for one family unwilling to be harassed at home. So, your long, hard fight, does it feel worth it now? Absolutely. Oh, yes. People shouldn't have to get up and move or relocate because you have a neighbor that is making your life miserable. We took our neighborhood back. If you're looking for some real estate, there's a nice house in white bear lake for sale, as lori christensen said, the biggest house on the block.

This transcript has been automatically generated and may not be 100% accurate.

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